The overall goal of this Cooperative Research Partnership is to develop a highly effective immunologic countermeasure to pulmonary infection with anthrax spores. The basic strategy of this application involves the development of a spore-based vaccine that combines killed, irradiated avirulent anthrax spores with powerful adjuvants to elicit immunity to inhalation anthrax. This Cooperative application represents a multi-disciplinary partnership combining microbiologists, immunologists, and chemists from two academic institutions, a non- profit research institution, and two biotechnology companies. The application responds specifically to the RFA request to develop countermeasures that target the spore phase of infection in the lung and mediastinal lymph nodes. Preliminary data shows that killed, irradiated spores from an avirulent anthrax strain, given with adjuvants, induce protective immunity by a novel mechanism requiring effector CD4+ T cells. Immunity to inhalation anthrax induced by spores develops rapidly and is independent of protective antigen (PA). This countermeasure targeted to spores represents a powerful complement to efforts focused on the induction of antibody responses to PA. The partnership provides innovative and practical approaches in an integrated effort focused on maximizing the effectiveness of the spore-based vaccine. The partnership has established the following milestones in the development process: Milestone 1: Develop effective adjuvants for the irradiated spore vaccine; Milestone 2: Analyze the efficacy and safety in mice of a variety of adjuvants for the irradiated spore vaccine, and compare intranasal and subcutaneous routes of administration; Milestone 3: Determine the mechanism of immune protection induced by the irradiated spore vaccine; Milestone 4: Identify correlates of protection in immunized mice; Milestone 5: Determine the efficacy of the most active vaccine/adjuvant combinations in protecting guinea pigs against fully virulent anthrax infection; Milestone 6: Determine the efficacy of the optimal vaccine/adjuvant combinations in protecting rabbits against fully virulent anthrax infection; Milestone 7: Determine safety, immunogenicity, and efficacy of the optimal spore/adjuvant vaccine combination using non-human primates The partnership will employ innovative chemical methods to develop novel adjuvants and preparations of adjuvant/spore combinations to maximize the CD4+ T cell response. Collaboration between microbiologists and immunologists will facilitate an understanding of the immunologic basis for protection against anthrax spores in the pulmonary tissues and will guide production and testing of the most effective vaccine. Collaborating investigators with expertise in the appropriate animal models of inhalation anthrax will demonstrate the effectiveness of the products ultimately selected by the iterative testing process. This project will enhance public health through protection against anthrax.